Get the percentage of pkgs that has been migrated to by-name

nixpkgs_by_name_progress.sh

export count=$(                                                        \
  curl -L "https://channels.nixos.org/nixos-unstable/packages.json.br" \
  | brotli -d --stdout                                                 \
  | nix run nixpkgs#jq -- ".packages | length")
find pkgs/by-name -maxdepth 1 -type d                                  \
  | xargs -i sh -c "find {} -maxdepth 1 -type d| wc -l"                \
  | tr '\n' '+'                                                        \
  | python -c "print(eval(input()[:-1]))"                              \
  | python -c "print(100 * int(input()) / $count, '%')"                \
  | head -c 7                                                          \
  | xargs printf "Percentage migrated: %s%%\n"